Tristan Thompson is averaging a double-double this year with good defense.

Since Anderson Varejao went down with injury in mid-December and Tristan was given a much bigger role on the team, he's averaging 13+ points, 10+ rebounds on 52% shooting and a block per game. That is over the course of 38 games... Not a small sample size.

I'd say it's obvious that Thompson has been better this year but I'd still rather have Williams because of his upside. Both these guys can be average starters but Williams has all-star talent and Thompson doesn't.